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Add Kaprekar number checker to special_numbers #12723

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Apply Ruff style fixes after renaming parameter
  • Loading branch information
Sean-Randall committed May 13, 2025
commit 1dd98c2c0ecebb4117fe6f322c8092de37eef65e
18 changes: 9 additions & 9 deletions maths/special_numbers/kaprekar_number.py
Original file line number Diff line number Diff line change
@@ -1,16 +1,16 @@
import math


def is_kaprekar_number(n: int) -> bool:
def is_kaprekar_number(number: int) -> bool:
"""
Determine whether a number is a Kaprekar number (excluding powers of 10).

A Kaprekar number is a positive number n such that:
n^2 = q * 10^m + r, for some m >= 1, q >= 0, 0 <= r < 10^m,
and n = q + r, with the restriction that n is not a power of 10.
A Kaprekar number is a positive number such that:
number^2 = q * 10^m + r, for some m >= 1, q >= 0, 0 <= r < 10^m,
and number = q + r, with the restriction that it is not a power of 10.

Args:
n (int): The number to check.
number (int): The number to check.

Returns:
bool: True if it's a Kaprekar number, else False.
@@ -25,14 +25,14 @@ def is_kaprekar_number(n: int) -> bool:
>>> is_kaprekar_number(1)
True
"""
if n == 1:
if number == 1:
return True
if n <= 0 or math.log10(n).is_integer():
if number <= 0 or math.log10(number).is_integer():
return False # Disallow powers of 10 (e.g., 10, 100, 1000)

square = str(n**2)
square = str(number ** 2)
for i in range(1, len(square)):
left, right = square[:i], square[i:]
if n == int(left or "0") + int(right):
if number == int(left or "0") + int(right):
return True
return False